/*
 * Copyright 2025 LinQingYing. and contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * The use of this source code is governed by the Apache License 2.0,
 * which allows users to freely use, modify, and distribute the code,
 * provided they adhere to the terms of the license.
 *
 * The software is provided "as-is", and the authors are not responsible for
 * any damages or issues arising from its use.
 *
 */

package org.cangnova.cangjie.resolve.scopes

import org.cangnova.cangjie.descriptors.ClassifierDescriptor
import org.cangnova.cangjie.descriptors.ClassifierDescriptorWithTypeParameters
import org.cangnova.cangjie.resolve.scopes.MemberScope
import com.intellij.util.SmartList

fun listOfNonEmptyScopes(scopes: Iterable<MemberScope?>): SmartList<MemberScope> =
    scopes.mapNotNull { it }.filterTo(SmartList()) { it !== MemberScope.Empty }

inline fun <Scope, T> getFirstFromAllScopes(scopes: Array<Scope>, callback: (Scope) -> T?): T? =
    when (scopes.size) {
        0 -> null
        1 -> callback(scopes[0])
        else -> {

            for (scope in scopes) {
                callback(scope)?.let {
                    return it
                }
            }
            null
        }
    }

inline fun <Scope, T : ClassifierDescriptor> getListClassifierDiscriminateHeaders(
    scopes: Array<Scope>,
    callback: (Scope) -> List<T>
): List<T> {
    val result = mutableListOf<T>()
    for (scope in scopes) {
        val newResult = callback(scope)
        if (newResult.isNotEmpty())
            result.addAll(newResult)
    }
    return result

}

/**
 * Concatenates the contents of this collection with the given collection, avoiding allocations if possible.
 * Can modify `this` if it is a mutable collection.
 */
fun <T> Collection<T>?.concat(collection: Collection<T>): Collection<T>? {
    if (collection.isEmpty()) {
        return this
    }
    if (this == null) {
        return collection
    }
    if (this is LinkedHashSet) {
        addAll(collection)
        return this
    }

    val result = LinkedHashSet(this)
    result.addAll(collection)
    return result
}
inline fun <Scope, T> getFromAllScopes(scopes: Array<Scope>, callback: (Scope) -> Collection<T>): Collection<T> =
    when (scopes.size) {
        0 -> emptyList()
        1 -> callback(scopes[0])
        else -> {
            var result: Collection<T>? = null
            for (scope in scopes) {
                result = result.concat(callback(scope))
            }
            result ?: emptySet()
        }
    }

inline fun <Scope, T : ClassifierDescriptor> getFirstClassifierDiscriminateHeaders(
    scopes: Array<Scope>,
    callback: (Scope) -> T?
): T? {
    // NOTE: This is performance-sensitive; please don't replace with map().firstOrNull()
    var result: T? = null
    for (scope in scopes) {
        val newResult = callback(scope)
        if (newResult != null) {
            if (newResult is ClassifierDescriptorWithTypeParameters /*&& newResult.isExpect*/) {
                if (result == null) result = newResult
            }
            // this class is Impl or usual class
            else {
                return newResult
            }
        }
    }
    return result
}

